The presidential debates kick off tonight, and that means it's time to power up your BS detection machines. The debates are often a heated affair with lots of broken logic arguments, but thankfully they're pretty easy to catch. Here's how to make sure you don't get duped.

Because of the quick response nature of the debates, presidential candidates often inadvertantly use a fallacy in their arguments. These are errors in reasoning where they divert the question, manipulate the viewer, or simply use facts selectively. It's the type of thing that would get you kicked off of a high school debate club.

To get a grasp on fallacies and debate skills, I spoke with Sam Nelson, the director of the Speech and Debate program at Cornell University, and Senior Lecturer at Cornell's Industrial and Labor Relations School. Before we get to ways you can spot fallacies in the debates (or during any argument you might have on your own), we have to get a good idea of how a fallacy works.

Get to Know Your Fallacies and Prime Your Brain for Skeptical Thinking

If witches are made of wood, they'll burn. Witches burn. Therefore they're made of wood.

Thankfully, spotting fallacies in arguments only requires a well-tuned ear. Author and scientist Carl Sagan offers this piece of advice when looking for fallacies in his book The Demon-Haunted World:

What skeptical thinking boils down to is the means to construct and to understand a reasoned argument, and, especially important, to recognize a fallacious or fraudulent argument. This question is not whether we like the conclusion that emerges out of a train of reasoning, but whether the conclusion follows from the premises or starting point, and whether that premise is true.

Part of that skeptical thinking toolkit is getting a base for what to look for, but it's also just paying close attention to the structure of a line of reasoning during the debates. Sagan's point is that you don't fall victim to your own confirmation bias and only agree on party lines. If you want to call out BS during the debates, you have to be watchful for the simple turns in logic and poor fallacious arguments. Photo by Carla Gates.

What to Look For in the Debates

The main purpose of the modern debates is to see the candidates under fire and see if they can keep a cool head. That calmness might seem like it makes it difficult to find problems with a candidate's arguments, but it's not as hard as you'd think. Nelson gave us a few simple tips for your BS detection toolkit. Photo by Paul Swansen.

The Gut Check

One of the easiest things you can do during the debates is to listen closely and pay attention to whether a statement rings true to you personally. Nelson calls this the gut check:

First of all, does it pass the gut check? Does [a statement] seem right? Oftentimes, your own common sense tells you that something doesn't seem correct. Maybe the impact of the argument is that you'll end up having to do something you don't think is correct. Generally, your own self-interest is a good test of whether or not an argument is true or false.

When you're watching the debates, pay attention to those last few lines of the argument where they're talking about the direct impact on you. If it rings false, the argument itself is probably flawed at some point, and you can always check it on FactCheck or Politifact.

Watch for Deflection

One of the common things you'll see during the debates is a deflection or non sequitur by one of the candidates. This often comes when they're asked a question, and they answer a similar (or in extreme cases, an entirely unrelated) question. The reasoning on their part is pretty simple according to Nelson:

Often times an advisor will tell a candidate that they need to get information out. Sometimes the opportunity to bring up a point doesn't come up in the questions. So, [candidates] kind of force it in. It's all about audience analysis. Sometimes it's better to seem non-responsive—to say the thing you desperately need to say to appeal to people—then it is to actually know what you're talking about.

It's a good idea to keep track of these deflections if you do want to know their thoughts on a particular issue. Deflections and non sequiturs were very common in the 2008 vice presidential debates.

Be Wary of an Appeal to Abstract Principles

A common tactic in the presidential debates is to use abstract principles to reel you into an idea. These are principles like "justice," "caring," or "freedom." The idea is that when you link a strong abstract principle to a policy, you're making it more appealing because everyone agrees with principles like "justice." Nelson suggests we'll likely see a lot of this in the debates:

So, say you have to sell something that you think is a bit of a bitter pill and not everyone will agree with you. What you do is you introduce an abstract principle and then you try to link it to your policy. The problem is that these are abstract principles and they can be linked to many policies in many different ways. In the debate game, whoever does a better job of explaining why their policies lead to these closely held abstract principles usually wins. I expect both sides to talk about general philosophical concepts. That should be a warning sign to us.

When you hear an abstract principle, start thinking twice about its relation to the policy you're being sold. For instance, if you hear something like, "My policy is about bringing [a concept] to justice," then you know something is probably off about the statement. It's the same tactic used in political ads, and as we know, advertising manipulates all types of things in your brain. Photo by nyghtowl.

Advertisements aren't inherently bad, but many use manipulative tactics that influence in ways …
Read more Read more

Listen for the Source of Statistics

Statistics are always a sticking point for the presidential debates, and for the most part none of us really know how to analyze them. Instead of being persuaded by the statistics, Nelson recommends you keep an ear out for their source:

One thing to look for is where the figures come from. If they say they're from the Government Accounting Office, that sounds legitimate. If they say they're "from a poll my campaign commissioned," then you want to consider the source.

Every day, we're confronted with claims that others present as fact. Some are easily debunked, …
Read more Read more

Don't Fall for Framing Tricks

Another popular trick in the debates is all about framing and branding an argument. These frames might include the catch phrases we've all come to know like "Obamacare," or "death tax." These phrases frame an issue in a certain light without actually describing what they mean. In turn, during the debates, we'll see the candidates attempt to reframe issues entirely. Nelson thinks they'll suggest that we've been thinking about issues incorrectly the entire time.

You will see both candidates saying, "The frame (they won't be using that word) you are using to talk about [the issue] is the wrong frame. This is how we should think about it." Then they'll use apple pie/red white and blue imagery to show why the whole way of thinking about these issues is wrong. Candidates understand that framing and branding is key, because people think in these broad metaphors.

We like a good catchphrase, and the candidates know that. When they're presenting their ideas about policy, don't be surprised when it gets a Kit-Kat-esque tagline along with it. It might make it more appealing because we like those broad metaphors, but it's important to keep in mind that the real frame you should be looking through is your own. Photo by Fibonacci Blue.

The Straw Man Argument

A very common fallacy in the presidential debates is the straw man. This is about creating the illusion that you're refuting an argument, but you're actually just responding to a weaker version of it. It's a common technique in the presidential debates. For instance, in 2008, Senator Obama uses an easy one (bolding ours):

Now, we also have to recognize that this is a final verdict on eight years of failed economic policies promoted by George Bush, supported by Senator McCain, a theory that basically says that we can shred regulations and consumer protections and give more and more to the most, and somehow prosperity will trickle down.

The one I imagine everyone will be able to see right away is the straw man—where you explain someone else's arguments in a weak way, so it's easy to knock down. A good strategy against that is sort of a reverse Straw man. Where you explain their argument, make it better for them, and then explain why it doesn't work. That's a much better argument.

The straw man is a simple to recognize fallacy, and one that's sure to show up in the debates at some point. Photo by Robin Ellis.

After the Debates: Check All the Facts

When all is said and done, it's about the facts. After the debates are over, it's always good to go back and check the validity of everything states so you don't get duped in the long run. Most major newspapers have a rundown after the debates are over, but you can also do a little research on your own.

FactCheck: FactCheck provides breakdowns of different things the candidates say and checks those facts against what they've said in the past, as well as the numbers.

PolitiFact: PolitiFact is similar to FactCheck, but also provides bite-sized tidbits for quick checking. They also have iPhone and Android apps to get facts on the go.

SuperPACApp: During the debates (and well after) you'll see a ton of political commercials. SuperPACApp is an iPhone app that works like Shazaam by listening to the ad, then pulling up relevant data about its claims.

Snopes: Snopes isn't exactly known for its political slant, but it is a solid place to check any historical arguments the candidates may make.

Regardless of your political affiliation, it's always good to keep an eye on the arguments during the debates. At best, it'll help you make an informed decision, but otherwise it'll help you better defend yourself during your own water cooler debate the next day.

You'll be able to watch the first debate live on YouTube, Xbox, and most major networks, tonight at 6 pm PST. For most places to stream, check out GigaOM's list.